First let me apologize if this is posted in the wrong forum. Long time reader/lurker first time poster! I recently upgraded my ATT line to an iPhone 5. I decided to keep my Nexus 4 and sell the iPhone to help with the costs of attending pharmacy school in the fall. I received instant payment from the person with verified paypal address so I promptly shipped out the phone but took some pictures of it before sending out.I have a video of me attempting to mail it via a 24 hour USPS kiosk drop box but alas it was locked. I have the original ATT receipts, pictures etc. as well as the USPS drop off receipt. It was delivered a week ago with delivery confirmation (and free shipping) to the buyer. The buyer is now claiming I sold him a used, blacklisted phone that can't be activated on ATT and has requested full refund. I'm frantic and about to go nuts, was banking on this money for my apartment for school! Any tips to resolving this? My Paypal account is now $-618.00 which is pretty disconcerting. Anyone ever deal with anything like this?